1. Field of the Invention
The present invention relates to a triboelectrically charging member.
2. Description of the Prior Art
Triboelectrically charging members are used in a variety of fields and are generally desirable due to their excellent triboelectrical chargeability, superior friction and heating resistance, and the stability of their triboelectric charging function over time.
These characteristics of triboelectrically charging members are specifically required in the field of electrophotographic developing apparatus. In dry developing apparatus which are monocomponent developers in particular, each time toner passes between the triboelectrically charging member and the developing roller, the toner must be uniformly thinned and adequately charged.
Conventional triboelectrically charging members (i.e., a toner thickness regulating member) are subject to various disadvantages such as when toner fused by frictional heating adheres to the surface of the charging member as a mass or film. Further disadvantages include markedly reduced copy image quality when so-called white streaks, black streaks, filming, grainy fog and the like, appear in the copy image, said defects being induced by uneven toner thickness, insufficient toner charging and uneven charging which are resulted from the defects that the triboelectrically charging member becomes worn or its surface is damaged over time due to toner-induced friction. Manufactured triboelectrically charging members in monocomponent dry developing systems have a further disadvantage in that they are constructed by affixing a film or sheet made from selected materials to an elastic metal substrate and therefore film component deformation and film separation at the ends of said member readily occur which gives rise to the aforesaid defects causing reductions in copy image quality.
Unexamined Japanese Patent Publications Sho 58-132769 and Sho 61-176961, for example, disclose the selections of poly-4-ethylene flouride resin or ethylene and 4-ethylene flouride copolymers as means for improving the release properties of the triboelectrically charging members. However, the triboelectrically charging members disclosed in these publications do not simultaneously fulfill requirements for release properties and friction resistance.